Clearly, we have only reproduced a small fraction of the known rank-two theories catalogued in [1]}. This is of course to be expected, since we searched only for theories whose Schur indices satisfy untwisted order-four MDEs. A preliminary analysis shows that the overwhelming majority of known rank-two theories satisfy twisted fourth-order MDEs.It remains an open question whether there is a universal upper bound on the order of the MDE for a fixed rank SCFT. For this reason, we anticipate that extending the current scan to the order-four twisted case would give even more interesting results.
